…ottle errors (#2146)

Fixes #2116.

Depends on #2134, #2144, #2145.

We've known that, especially for sandbox accounts with lots of
purchases, the SDK can get flooded with a lot of transactions to process
at once.
I've been making some improvements for this (like #2115).

Another consequence of this behavior, is that we can end up failing due
to `StoreKit` throttling us (see #2116):

> 2022-12-03 12:31:58.670892+0100 app[673:61074]
<SKReceiptRefreshRequest: 0x283edc860>: Finished refreshing receipt with
error: Error Domain=ASDErrorDomain Code=603 "Request throttled"
UserInfo={NSLocalizedFailureReason=Unified receipt is valid and current,
NSLocalizedDescription=Request throttled, AMSServerErrorCode=0}

This change avoids that by skipping the refresh if less than 2 seconds
have elapsed. I chose 2 to make this a low-ish risk change, with a huge
benefit for multiple semi-concurrent requests coming from a big
transaction queue.

**This is an automatic release.**

### Bugfixes
* Fix sending presentedOfferingIdentifier in StoreKit2 (#2156) via Toni
Rico (@tonidero)
* `ReceiptFetcher`: throttle receipt refreshing to avoid `StoreKit`
throttle errors (#2146) via NachoSoto (@NachoSoto)
### Other Changes
* Added integration and unit tests to verify observer mode behavior
(#2069) via NachoSoto (@NachoSoto)
* Created `ClockType` and `TestClock` to be able to mock time (#2145)
via NachoSoto (@NachoSoto)
* Extracted `asyncWait` to poll `async` conditions in tests (#2134) via
NachoSoto (@NachoSoto)
* `StoreKitRequestFetcher`: added log when starting/ending requests
(#2151) via NachoSoto (@NachoSoto)
* `CI`: fixed `PurchaseTester` deployment (#2147) via NachoSoto
(@NachoSoto)